Effects of PI3K Inhibitor NVP-BKM120 on Acquired Resistance to Gefitinib of Human Lung Adenocarcinoma H1975 Cells

The effects of class I PI3K inhibitor NVP-BKM120 on cell proliferation, cell cycle distri- bution, cellular apoptosis, phosphorylation of several proteins of the PI3K/AKT signaling pathway and the mRNA expression levels of HIFl-ct, VEGF and MMP9 in the acquired gefitinib resistant cell line H1975 were investigated, and whether NVP-BKM120 can overcome the acquired resistance caused by the EGFR T790M mutation and the underlying mechanism were explored. MTT assay was performed to detect the effect of gefitinib, NVP-BKM120, NVP-BKM120 plus 1 ~unol/L gefitinib on growth of H1975 cells. The distribution of cell cycle and apoptosis rate of H1975 cells were examined by using flow cytometry. The mRNA expression levels of tumor-related genes such as HIFI-a, VEGF and MMP9 were detected by using real-time quantitative PCR. Western blotting was used to detect the ex- pression level of phosphorylated proteins in the PI3K/AKT signaling pathway, such as Ser473-p-AKT, Ser235/236-p-S6 and Thr70-p-4E-BP1, as well as total AKT, $6 and 4E-BP1. The results showed that the NVP-BKM120 could inhibit the growth of H1975 cells in a concentration-dependent manner, and H1975 cells were more sensitive to NVP-BKM120 than gefitinib （IC50：1.385 vs. 15.09 ~mol/L respec- tively）, whereas combination of NVP-BKM120 and gefitinib （1 ~trnol/L） did not show more obvious ef- fect than NVP-BKM120 used alone on inhibition of cell growth （P〉0.05）. NVP-BKM120 （1 ~unol/L） increased the proportion ofH1975 cells in G0~G1 phase and the effect was concentration-dependent, and 2 ~maol/L NVP-BKM120 promoted apoptosis ofH1975 cells. There was no significant difference in the proportion of H1975 cells in G0-G1 phase and apoptosis rate between NVP-BKM120-treated alone group and NVP-BKM120 plus genfitinib （1 ~unol/L）-treated group or between DMSO-treated control group and gefitinib （1 Ixmol/L）-treated alone group （P〉0.05 for all）. It was also found that the mRNA expression levels of these genes were down-regulated by NVP-BKM120 （1 ~unol/L）, and NVP-BKM120 （1 ~tmol/L） or NVP-BKM120 （1 pmol/L） plus gefitinib （1 ~tmol/L） obviously inhibited the activation of Akt, $6 and 4E-BP1 as compared with control group, but single use of gefitinib （1 pmol/L） exerted no significant effect. These data suggested that NVP-BKM120 can overcome gefitinib resistance in H1975 cells, and the combination of NVP-BKM120 and gefitinib did not have additive or synergistic effects. It was also concluded that NVP-BKM120 could overcome the acquired resistance to gefitinib by down-regulating the phosphorylated protein in PI3K/AKT signal pathways in H1975 cells, but it could not enhance the sensitivity of H 1975 cells to gefitinib.

Efficacy of pemetrexed combined with erlotinib/gefitinib in advanced non-small cell lung cancer patients during tyrosine kinase inhibitor treatment

Objective We aimed to evaluate the efficacy and safety of pemetrexed combined with erlotinib/gefitinib in advanced non-small cell lung cancer(NSCLC) patients during tyrosine kinase inhibitor(TKI) treatment. Methods Thirty-two patients with advanced NSCLC were divided into two groups. Patients in the control group received continuous daily epidermal growth factor receptor tyrosine kinase inhibitor(EGFRTKI) treatment, and patients in the experimental group received continuous daily EGFR-TKI along with pemetrexed treatment, which was administered on day 1 at 500 mg/m2. Erlotinib(150 mg) or gefitinib(250 mg) was administered daily from day 1 to day 21, with a cycle of every 21 days. Dexamethasone, folic acid, and vitamin B12 were also administered during the treatment. The endpoint of the primary study was the disease control rate. Results The objective response rate was 21.9%(95% CI: 7.6% to 36.3%) in the control group, whereas the disease control rate was 84.4%(95% CI: 71.8% to 97.0%) in the experimental group. The median progression-free survival was 6.2(95% CI: 2.4 to 10.0). Grades 3 or 4 adverse effects of leucopenia(15.6%), neutropenia(12.5%), anemia(3.1%), and nausea or vomiting(3.1%) were found in the experimental group.Conclusion The administration of pemetrexed combined with erlotinib or gefitinib showed a higher efficacy in TKI-resistant NSCLC patients. Further, the adverse effects of this drug combination were well tolerated by the patients. Pemetrexed combined with TKI treatment might provide a satisfactory therapeutic strategy for advanced NSCLC patients after TKI treatment.